The MPEG 4 standard relates to the coding of audiovisual objects for scene composition. The advantages of separate coding of the objects are known. For example, better data compression is obtained owing to the segmentation of the images making it possible to code with an image quality which is dependent on the zones of interest or to store the coding data of objects at the coder level, avoiding the retransmission of the corresponding data. Also, it is possible to construct scenes with great flexibility, which scenes can be created or modified at the coder level independently of the information received.
The MPEG 2 type coding and decoding circuits, according to the prior art, do not make it possible to utilize video objects and hence do not allow a scene to be composed in a simple and flexible manner as in the MPEG 4 standard.